ugly emotion
Try having your parents constantly remind you how they prefer your sibling and how better they are and how much more loved they are. When the most important people make you feel worthless and unloved, you feel envy for the ones who gets the love and attention.
You are right. Everything you said is truth, but that is not his brother's fault, it's his parents fault. I was in that situation, and I felt envy towards my little sister, you know? It was a terrible feeling, because I'm really close with my baby-sister, even if we are not blood related, and we have eight years of difference. Being envious of her was one of the most miserable things I've ever felt, and I was awfully ashamed for resenting her. But I really love her, so I never treated her bad just because I felt small, stupid and unloved in comparision. And, eventually, I stoped feeling that way. I still think envy, jealousy and hate are terrible emotions. They make people feel miserable and unhappy, and they serve for nothing. The ugly thing is when people hurt others because of those king of feelings.
remember that he was young. his mother's neglectful treatment made it worse, and so it became uncontrollable for him.
and just saying, i've also been in his shoes where i felt less than my younger brother (though definitely nowhere near as bad as Makoto's situation) growing up and i still go through slight throes of experiences/emotions after 20 years. you don't get over it quickly, and jealousy/ugly emotions allow you to grow, like i have.
Your typos aren't very pretty to look at either, proofreading is always a good idea.
I liked Hajime's story a lot more. Envy is such an ugky emotion. :/